hi,

• the description is incomplete: what about 2 and 5 digits? you need to give the complete table of equivalences between digits.
• what's the supposed input range? (max upper value, for instance)
• are the boundaries inclusive or exclusive or inclusive/exclusive?
• mihght be very close to other already existing katas:
  • Upside-Down Numbers
  • Upside-Down Numbers - harder
  • any kata about primes

=> sure that far enough of any of those to not be a duplicate?

Done => no, that's way too close from the other upside-down katas.

in addition:

• not enough tests
• not enough random tests
• lacking most of the important edge cases (boundaries on strobo primes)
• again, lacking too much information in the desription

please unpublish it.